MIM capacitor formation in RMG module

ABSTRACT

A method is provided for forming a metal-insulator-metal capacitor in a replacement metal gate module. The method includes providing a gate cap formed on a gate. The method further includes removing a portion of the gate cap and forming a recess in the gate. A remaining portion of the gate forms a first electrode of the capacitor. The method also includes depositing a dielectric on remaining portions of the gate cap and the remaining portion of the gate. The method additionally includes depositing a conductive material on the dielectric. The method further includes removing a portion of the conductive material and portions of the dielectric to expose a remaining portion of the conductive material and a remaining portion of the dielectric. The remaining portion of the conductive material forms a second electrode of the capacitor. The remaining portion of the dielectric forms an insulator of the capacitor.

BACKGROUND

1. Technical Field

The present invention relates generally to microelectronics circuitsand, in particular, to metal-insulator-metal (MIM) capacitor formationin a replacement metal gate (RMG) module.

2. Description of the Related Art

The Metal-Insulator-Metal capacitor is a key passive component in RadioFrequency (RF) and analog integrated circuits. MIM capacitors haveattracted great attention because of their high capacitance density thatsupplies small area, increases circuit density, and further reduces thefabrication cost. MIM capacitors provide good voltage linearityproperties.

SUMMARY

According to an aspect of the present principles, a method is providedfor forming a metal-insulator-metal capacitor in a replacement metalgate module. The method includes providing a gate cap formed on a gate.The method further includes removing a portion of the gate cap andforming a recess in the gate. A remaining portion of the gate forms afirst electrode of the capacitor. The method also includes depositing adielectric on remaining portions of the gate cap and the remainingportion of the gate. The method additionally includes depositing aconductive material on the dielectric. The method further includesremoving a portion of the conductive material and portions of thedielectric to expose a remaining portion of the conductive material anda remaining portion of the dielectric. The remaining portion of theconductive material forms a second electrode of the capacitor. Theremaining portion of the dielectric forms an insulator of the capacitor.

According to another aspect of the present principles, a method isprovided for forming a metal-insulator-metal capacitor in a replacementmetal gate module. The method includes providing a gate cap formed on agate. The method further includes forming a plurality of recesses byforming a plurality of voids in the gate cap and forming a plurality ofgate recesses in the gate under the plurality of voids. A remainingportion of the gate forms a first electrode of the capacitor. The methodalso includes depositing a dielectric on remaining portions of the gatecap and the remaining portion of the gate. The method additionallyincludes depositing a conductive material on the dielectric. The methodfurther includes removing a plurality of portions of the dielectric anda remaining portion of the conductive material to expose a plurality ofremaining portions of the dielectric and a plurality of remainingportions of the conductive material. The plurality of remaining portionsof the dielectric form at least a portion of an insulator of thecapacitor. The plurality of remaining portions of the conductivematerial form a second electrode of the capacitor.

According to yet another aspect of the present principles, ametal-insulator-metal capacitor is provided in a replacement metal gatemodule having a gate cap formed on a gate. The capacitor includes afirst electrode formed within a portion of the gate using a metalforming the gate. The first electrode has a horizontal component and astack rising from at least a portion of the horizontal component. Thecapacitor further includes an insulator formed within a recess. Therecess is formed to have a lower portion and walls rising from edges ofthe lower portion. The lower portion is formed on a different portion ofthe horizontal component than the stack. The walls are formed adjacentto a sidewall of the stack and a portion of the gate cap. The capacitoralso includes a second electrode formed within the recess and on theinsulator.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1 shows an exemplary method 100 for metal-insulator-metal capacitorformation in a replacement metal gate (RMG) module, in accordance withan embodiment of the present principles;

FIG. 2 shows a cross-sectional view of a metal-insulator-metal capacitorat step 110 of method 100, according to an embodiment of the presentprinciples;

FIG. 3 shows a cross-sectional view of a metal-insulator-metal capacitorat step 120 of method 100, according to an embodiment of the presentprinciples;

FIG. 4 shows a cross-sectional view of a metal-insulator-metal capacitorat step 130 of method 100, according to an embodiment of the presentprinciples;

FIG. 5 shows a cross-sectional view of a metal-insulator-metal capacitorat step 140 of method 100, according to an embodiment of the presentprinciples;

FIG. 6 shows a cross-sectional view of a metal-insulator-metal capacitorat step 150 of method 100, according to an embodiment of the presentprinciples;

FIG. 7 shows another exemplary method 700 for metal-insulator-metalcapacitor formation in a replacement metal gate (RMG) module, inaccordance with an embodiment of the present principles;

FIG. 8 shows a cross-sectional view of a metal-insulator-metal capacitorat step 710 of method 700, according to an embodiment of the presentprinciples;

FIG. 9 shows a cross-sectional view of a metal-insulator-metal capacitorat step 720 of method 700, according to an embodiment of the presentprinciples;

FIG. 10 shows a cross-sectional view of a metal-insulator-metalcapacitor at step 725 of method 700, according to an embodiment of thepresent principles;

FIG. 11 shows a cross-sectional view of a metal-insulator-metalcapacitor at step 730 of method 700, according to an embodiment of thepresent principles;

FIG. 12 shows a cross-sectional view of a metal-insulator-metalcapacitor at step 740 of method 700, according to an embodiment of thepresent principles; and

FIG. 13 shows a cross-sectional view of a metal-insulator-metalcapacitor at step 750 of method 700, according to an embodiment of thepresent principles.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present principles are directed to metal-insulator-metal (MIM)capacitor formation in a replacement metal gate (RMG) module.

FIG. 1 shows an exemplary method 100 for metal-insulator-metal capacitorformation in a replacement metal gate (RMG) module, in accordance withan embodiment of the present principles. FIGS. 2-6 show variouscross-sectional views of a metal-insulator-metal capacitor at varioussteps in method 100, according to an embodiment of the presentprinciples. At least the following correlations apply: step 110 (FIG.2); step 120 (FIG. 3); step 130 (FIG. 4); step 140 (FIG. 5); and step150 (FIG. 6).

At step 110 (FIG. 2), commence method 100 post (after) formation of agate cap 201GC on an underlying gate 202UG.

In an embodiment, the underlying gate 202UG is formed from a metal(hereinafter “gate metal”), and thus both (the underlying gate and thegate metal) are interchangeably referred to herein by the referencecharacters 202UG. In an embodiment, the gate metal 202UG is Tungsten(W). Of course, other materials can be used for the gate metal 202UG,while maintaining the spirit of the present principles.

In an embodiment, the gate cap 201GC is formed using a dielectric(hereinafter “gate cap dielectric”). In an embodiment, the gate capdielectric is a high K dielectric. Of course, other types of dielectricscan be used, while maintaining the spirit of the present principles.

At step 120 (FIG. 3), remove a portion of the gate cap 201GC and form arecess 211 in the underlying gate 202UG. The remaining portion of theunderlying gate 202UG forms a first electrode 210C of MIM capacitor 200as shown in FIG. 6.

At step 130 (FIG. 4), deposit a dielectric 215 on remaining portions ofthe gate cap 201GC and the remaining portion of the underlying gate202UG. Deposit conductive material 220 on the dielectric 215.

In an embodiment, the dielectric 215 is a high K dielectric. Of course,other types of dielectrics can be used, while maintaining the spirit ofthe present principles.

In an embodiment, the conductive material 220 is Titaniumnitride/Tungsten (TiN/W). Of course, other conductive materials can beused, while maintaining the spirit of the present principles.

At step 140 (FIG. 5), remove a portion of the conductive material 220and portions of the dielectric 215 to expose a remaining portion of theconductive material 220 and a remaining portion of the dielectric 215.The remaining portion of the conductive material 220 forms a secondelectrode 220C of MIM capacitor 200 as shown in FIG. 6. The remainingportion of the dielectric 215 forms an insulator 215C of MIM capacitor200 as shown in FIG. 6.

In an embodiment, such as that shown in FIG. 1, step 140 involvesremoving selected (topmost) horizontal components of the dielectric 215deposited at step 130 so only the vertical components (walls) and anunselected (bottommost) horizontal component of the dielectric 215remain.

In an embodiment, step 140 involves polishing, patterning, etching,and/or any other technique to remove portions from materials 215 and220.

At step 150 (FIG. 6), form respective contacts 231C and 232C onelectrodes 210C and 220C thus forming MIM capacitor 200.

It is to be appreciated that each of the preceding layers/elements shownin FIGS. 2-6 can be formed or printed optically through well-knownphotolithographic masking, developing and level definition, e.g.,depositing, implanting, patterning, etching, polishing, and so forth.Thus, the present principles are not limited to any particular processfor forming the layers/elements shown in FIGS. 2-6.

It is to be further appreciated that the gate cap can be formed from thesame dielectric material or a different dielectric material than thatdeposited at step 130. Moreover, while a high K dielectric is describedas being deposited at step 130, a non-high K dielectric can also be usedin place thereof while maintaining the spirit of the present principles.

FIG. 7 shows another exemplary method 700 for metal-insulator-metalcapacitor formation in a replacement metal gate (RMG) module, inaccordance with an embodiment of the present principles. FIGS. 8-13 showvarious cross-sectional views of a metal-insulator-metal capacitor atvarious steps in method 700, according to an embodiment of the presentprinciples. At least the following correlations apply: step 710 (FIG.8); step 720 (FIG. 9); step 725 (FIG. 10); step 730 (FIG. 11); step 740(FIG. 12); and step 750 (FIG. 13).

At step 710 (FIG. 8), commence method 700 post (after) formation of agate cap 801GC on an underlying gate 202UG.

In an embodiment, the underlying gate 802UG is formed from a metal(hereinafter “gate metal”), and thus both (the underlying gate and thegate metal) are interchangeably referred to herein by the referencecharacters 802UG. In an embodiment, the gate metal 802UG is Tungsten(W). Of course, other materials can be used for the gate metal 802UG,while maintaining the spirit of the present principles.

In an embodiment, the gate cap 801GC is formed using a dielectric(hereinafter “gate cap dielectric”). In an embodiment, the gate capdielectric is a high K dielectric. Of course, other types of dielectricscan be used, while maintaining the spirit of the present principles.

At step 720 (FIG. 9), remove portions of the gate cap 801GC to formvoids 211A in the gate cap 801GC.

At step 725 (FIG. 10), remove portions of the underlying gate 802 toform recesses 811B in the underlying gate 802. The recesses 811B areformed under the voids 811A. The remaining portions of the underlyinggate 802UG form a first electrode 810C of MIM capacitor 800 as shown inFIG. 13.

At step 730 (FIG. 11), deposit a dielectric 815 on remaining portions ofthe gate cap 801GC and the remaining portion of the underlying gate802UG. Deposit conductive material 820 on the dielectric 815.

In an embodiment, the dielectric 815 is a high K dielectric. Of course,other types of dielectrics can be used, while maintaining the spirit ofthe present principles.

In an embodiment, the conductive material 820 is Titaniumnitride/Tungsten (TiN/W). Of course, other conductive materials can beused, while maintaining the spirit of the present principles.

At step 740 (FIG. 12), remove portions of the dielectric 815 and aportion of the conductive material 820 to expose remaining portions ofthe dielectric 815 and remaining portions of the conductive material820. The remaining portions of the dielectric 815 form at least part ofan insulator 815C of MIM capacitor 800 as shown in FIG. 13. At leastsome of the remaining portions of the gate cap 801GC also form insulator815C as shown in FIG. 13. The remaining portions of the conductivematerial 820 form a second electrode 820C of MIM capacitor 800 as shownin FIG. 13.

In an embodiment, such as that shown in FIG. 7, step 740 involvesremoving selected (topmost) horizontal components of the high Kdielectric 815 deposited at step 730 so only the vertical components(walls) and unselected (bottommost) horizontal components of thedielectric 815 remain.

In an embodiment, step 740 involves polishing, patterning, etching,and/or any other technique to remove portions from materials 815 and820.

At step 750 (FIG. 13), form respective contacts 831C and 832C onelectrodes 810C and 820C thus forming MIM capacitor 800.

As is evident to one of ordinary skill in the art, the structure of MIMcapacitor 800 has an increased area compared to MIM capacitor 200.

It is to be appreciated that each of the preceding layers/elements shownin FIGS. 8-13 can be formed or printed optically through well-knownphotolithographic masking, developing and level definition, e.g.,depositing, implanting, patterning, etching, polishing, and so forth.Thus, the present principles are not limited to any particular processfor forming the layers/elements shown in FIGS. 8-13.

It is to be further appreciated that the gate cap can be formed from thesame dielectric material or a different dielectric material than thatdeposited at step 130. Moreover, while a high K dielectric is describedas being deposited at step 130, a non-high K dielectric can also be usedin place thereof while maintaining the spirit of the present principles.

It is to be additionally appreciated that the present principles form aMIM capacitor within a gate(s) of another device(s) (and, thus, can alsobe formed on a region of the other device(s) without any semiconductormaterial present), as well as use the gate metal of the other device(s)as one of the electrodes, thereby simplifying the flow in contrast toprior art approaches such as those that use source/drain (S/D) and gateregions to form capacitors.

We note that as compared to prior art which forms capacitors in a moreclassical fashion (layer-by-layer in a separate region), the presentprinciples use the gate material as one of the stacks as well as formthe capacitor in the gate region(s), resulting in a simpler flow.

We further note that the present principles do not suffer fromlimitations such as the capacitor insulator thickness being determinedby contact etch (therefore making such thickness essentially variable).Rather, the present principles form a capacitor structure within thegate(s) by recessing the metal (which is used as the first electrode),then depositing the capacitor insulator (which, hence, is verycontrolled), followed by the second electrode deposition.

The present invention may be a system, a method, and/or a computerprogram product. The computer program product may include a computerreadable storage medium (or media) having computer readable programinstructions thereon for causing a processor to carry out aspects of thepresent invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java, Smalltalk, C++ or the like,and conventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present principles, as well as other variations thereof, means thata particular feature, structure, characteristic, and so forth describedin connection with the embodiment is included in at least one embodimentof the present principles. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This may be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

Having described preferred embodiments of a system and method (which areintended to be illustrative and not limiting), it is noted thatmodifications and variations can be made by persons skilled in the artin light of the above teachings. It is therefore to be understood thatchanges may be made in the particular embodiments disclosed which arewithin the scope of the invention as outlined by the appended claims.Having thus described aspects of the invention, with the details andparticularity required by the patent laws, what is claimed and desiredprotected by Letters Patent is set forth in the appended claims.

What is claimed is:
 1. A method for forming a metal-insulator-metalcapacitor in a replacement metal gate module, comprising: providing agate cap formed on a gate; removing a portion of the gate cap andforming a recess in the gate, a remaining portion of the gate forming afirst electrode of the capacitor; depositing a dielectric on remainingportions of the gate cap and the remaining portion of the gate;depositing a conductive material on the dielectric; and removing aportion of the conductive material and portions of the dielectric toexpose a remaining portion of the conductive material and a remainingportion of the dielectric, the remaining portion of the conductivematerial forming a second electrode of the capacitor, and the remainingportion of the dielectric forming an insulator of the capacitor.
 2. Themethod of claim 1, further comprising forming respective contacts on thefirst and second electrodes.
 3. The method of claim 1, whereindepositing the conductive material on the dielectric comprises filling aportion of the recess with the conductive material.
 4. The method ofclaim 1, wherein removing respective portions of the dielectriccomprises removing a selected horizontal component of the dielectric soonly vertical components and a single unselected horizontal component ofthe dielectric remain.
 5. The method of claim 1, wherein at least aportion of the capacitor is formed within a gate of a field effectstransistor.
 6. The method of claim 1, wherein at least a portion of thecapacitor is formed on a region of a field effects transistor, theregion being without any semiconductor present.
 7. The method of claim1, wherein said forming step uses a gate metal of the field effecttransistor as the first electrode of the capacitor.
 8. The method ofclaim 1, wherein the gate is formed from Tungsten.
 9. The method ofclaim 1, wherein the conductive material is Titanium nitride/Tungsten.10. The method of claim 1, wherein said removing step removes therespective portions of the conductive material and the dielectric downto a surface of the gate cap.
 11. The method of claim 10, wherein thesurface of the gate cap down to which the respective portions of theconductive material are removed is one of a top surface and anintermediate surface.